The Scadden laboratory focuses on stem cell interactions with their niche. Stem cell function is governed by input from local and systemic environments that determine how the stem cell pool contributes to the basic physiologic processes of tissue growth, maintenance and repair. Disturbance of the interaction between stem and niche cells can change the persistence of stem cells or distort their ordered differentiation and result in neoplasia. We study the hematopoietic system in mouse and man to define the nature of the stem cell – niche relationship and how it may be manipulated to alter the outcome of hematologic disease.